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United States Patent |
5,276,067
|
Doerge
|
January 4, 1994
|
HCFC blown rigid foams with low thermal conductivity
Abstract
Rigid polyurethane foams having low thermal conductivity values are
produced by reacting an organic polyisocyanate with an organic material
having at least two isocyanate reactive hydrogen atoms and an OH value of
from about 200 to about 650 in the presence of a blowing agent. The
blowing agent is a mixture of 1,1-dichloro-2,2,2-trifluoroethane
(HCFC-123) or dichlorofluoroethane (HCFC-141b) and from about 0.1 to about
1.0% by weight (based on total weight of the foam forming mixture) water.
The foams obtained are characterized by a thermal conductivity of less
than about 0.130 Btu-in./hr.ft.sup.2 .degree.F., preferably less than
about 0.120 Btu-in./hr.ft.sup.2 .degree.F. These foams are particularly
useful as insulation materials.
Inventors:
|
Doerge; Herman P. (Pittsburgh, PA)
|
Assignee:
|
Miles Inc. (Pittsburgh, PA)
|
Appl. No.:
|
053792 |
Filed:
|
April 27, 1993 |
Current U.S. Class: |
521/131; 521/155 |
Intern'l Class: |
C08J 009/14 |
Field of Search: |
521/131,155
|
References Cited
U.S. Patent Documents
4927863 | May., 1990 | Bartlett et al. | 521/131.
|
4943597 | Jul., 1990 | Grunbauer et al. | 521/167.
|
4945119 | Jul., 1990 | Smits et al. | 521/131.
|
4960804 | Oct., 1990 | Doerge | 521/130.
|
Other References
Database, WPIL, wk 9025, May 10, 1990, AN 188939 & JP-A-2 123 119
(Matsushita Reiki K.K.)-Abstract.
Chemical Abstract No. 113(16)133885r.
Database WPIL, wk 9129, Jun. 11, 1991, AN 213185, & JP-A-3 137 138
(Matsushita Reiki K.K.)-abstract, Chemical Abstract, No. 116(2)7405h.
|
Primary Examiner: Foelak; Morton
Attorney, Agent or Firm: Gil; Joseph C., Whalen; Lyndanne M.
Parent Case Text
This application is a division of application Ser. No. 07/763,109 filed
Sep. 20, 1991, now U.S. Pat. No. 5,254,601.
Claims
What is claimed is:
1. A rigid polyurethane foam having a thermal conductivity of less than
about 0.130 Btu-in/hr.ft.sup.2 .degree.F. which is the reaction product of
a) an organic polyisocyanate with
b) an organic material having at least two isocyanate reactive hydrogen
atoms and an OH value of from about 200 to about 650
in the presence of
c) from about 0.1 to about 1.0% by weight, based upon the total weight of
the foam forming components, of water and
d) a blowing agent selected from the group consisting of
1,1-dichloro-2,2,2-trifluoroethane and dichlorofluoroethane.
2. The foam of claim 1 in which from about 0.15% to about 0.6% by weight of
water was present during its formation.
3. The foam of claim 1 having a thermal conductivity of less than 0.120
Btu-in./hr.ft.sup.2 .degree.F.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a process for producing rigid polyurethane
foams having a thermal conductivity of less than about 0.130
Btu-in./hr.ft.sup.2 .degree.F. and to the foams produced by this process.
Rigid polyurethane foams and processes for their production are well known
in the art. Such foams are typically produced by reacting a polyisocyanate
with an isocyanate-reactive material such as a polyol in the presence of a
chlorofluorocarbon blowing agent. It is also known, however, that these
chlorofluorocarbon blowing agents pose environmental problems.
Alternatives to the known chlorofluorocarbon blowing agents are currently
the subject of much research. Hydrogen chlorofluorocarbons (HCFC) are
among the most promising alternatives. However, some HCFCs must be used in
larger amounts than the traditional chlorofluorocarbons and often result
in foams having thinner cell walls. The HCFCs also tend to migrate from
foam cell cavities thereby reducing the insulation value of the foam.
Further, HCFCs produce a more thermally conductive foam insulation which
reduces the energy efficiency of appliances, e.g., which are insulated
with such foams. Consequently, substitution of HCFCs for the traditional
chlorofluorocarbons may resolve the environmental problems created by
chlorofluorocarbons but it creates an energy efficiency problem. It would
therefore be advantageous to develop a process for producing energy
efficient, rigid polyurethane foams in which none of the traditional
chlorofluorocarbon blowing agents was employed.
One approach to resolving the migration problem of HCFCs has been to use
mixtures of the traditional chlorofluorocarbons and the HCFCs. This
approach is disclosed in U.S. Pat. Nos. 4,927,863 and 4,945,119. These
blowing agent mixtures do, however, include some of the undesirable
traditional chlorofluorocarbons.
U.S. Pat. No. 4,943,597 discloses a process for producing rigid
polyurethane foams in which water is used as the blowing agent. Other
optional blowing agents disclosed in this patent include the known low
boiling halogenated halocarbons and "azo" blowing agents.
U.S. Pat. No. 4,960,804 discloses a process for producing rigid foams in
which a mixture of an HCFC and an alkyl alkanoate is used as the blowing
agent.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a process for the
production of rigid polyurethane foams in which none of the traditional
chlorofluorocarbon blowing agents are employed.
It is also an object of the present invention to provide a process for the
production of rigid polyurethane foams having a low thermal conductivity
in which a chlorofluorocarbon is not employed.
It is a further object of the present invention to provide low thermal
conductivity rigid polyurethane foams.
These and other objects which will be apparent to those skilled in the art
are accomplished by reacting an organic polyisocyanate with an organic
material having at least two isocyanate reactive hydrogen atoms in the
presence of a blowing agent which is a mixture of water and either
dichlorofluoroethane (HCFC-141b) or 1,1-dichloro-2,2,2-trifluoroethane
(HCFC-123). The water must be present in an amount of from about 0.1 to
about 1.0% by weight of the total foam forming mixture. The resultant
foams are characterized by a thermal conductivity of less than about
0.130, preferably less than about 0.120 Btu-in./hr.ft.sup.2 .degree.F.
DETAILED DESCRIPTION OF THE INVENTION
In the process of the present invention, an organic polyisocyanate is
reacted with an organic material having at least two isocyanate reactive
hydrogen atoms in the presence of a mixture of water and either
1,1-dichloro-2,2,2-trifluoroethane (HCFC-123) or dichlorofluoroethane
(HCFC-141b). The HCFC-123 and HCFC-141b are commercially available and may
generally be included in the reaction mixture in an amount of from about
10 to about 22% by weight, preferably from about 15 to about 20% by
weight, and most preferably about 16-18% by weight, based upon the total
weight of the foam forming mixture.
The water included in the foam forming mixture is generally included in an
amount of from about 0.1 to about 1.0% by weight, preferably from about
0.15 to about 0.60% by weight, and most preferably about 0.2% by weight,
based upon the total weight of the foam forming mixture.
The HCFC-123 or HCFC-141b and water may be added individually to the foam
forming reaction mixture but it is preferred that the HCFC-123 or
HCFC-141b and water be combined to form a mixture prior to addition to the
foam forming mixture.
Any of the known organic polyisocyanates may be used in the process of the
present invention. Suitable polyisocyanates include: aromatic, aliphatic
and cycloaliphatic polyisocyanates and combinations thereof.
Representative of these types are diisocyanates such as m- or p-phenylene
diisocyanate, toluene-2,4-diisocyanate, toluene-2,6-diisocyanate,
hexamethylene-1,6-diisocyanate, tetramethylene-1,4-diisocyanate,
cyclohexane,1,4-diisocyanate, hexahydrotoluene diisocyanate (and isomers),
naphthylene-1,5-diisocyanate, 1-methylphenyl-2,4-phenyl diisocyanate,
diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate,
4,4'-biphenylene diisocyanate, 3,3'-dimethoxy-4,4'-biphenylene
diisocyanate and 3,3'-dimethyl-diphenylpropane-4,4'-diisocyanate;
triisocyanates such as toluene-2,4,6-triisocyanate and polyisocyanates
such as 4,4'-dimethyldiphenylmethane-2,2',5,5'-tetraisocyanate and the
diverse polymethylenepolyphenylpolyisocyanates.
A crude polyisocyanate may also be used in making polyurethanes, such as
the crude toluene diisocyanate obtained by the phosgenation of a mixture
of toluene diamines or the crude diphenylmethane diisocyanate obtained by
the phosgenation of crude diphenylmethanediamine. The preferred
undistilled or crude polyisocyanates are disclosed in U.S. Pat. No.
3,215,652, incorporated by reference.
Especially preferred for making rigid polyurethanes are methylene-bridged
polyphenyl/polyisocyanates and prepolymers of methylene-bridged
polyphenyl/polyisocyanates, having an average functionality of from about
1.8 to about 3.5, preferably about 2.0 to about 3.1 isocyanate moieties
per molecule and an NCO content of from about 28 to about 34% by weight,
due to their ability to cross-link the polyurethane. The isocyanate index
(ratio of equivalents of isocyanates to equivalents of active
hydrogen-containing groups) is advantageously from about 0.9 to about 3.0,
preferably about 1.0 to about 2.0 and most preferably from about 1.0 to
about 1.5.
Any of the known organic compounds but preferably polyols containing at
least two isocyanate-reactive hydrogen atoms and having a hydroxyl (OH)
value of from about 200 to about 650, preferably from about 400 to about
500, may be employed in the process of the present invention.
Suitable high functionality, high molecular weight polyols may be prepared
by reacting a suitable initiator containing active hydrogens with alkylene
oxide. Suitable initiators are those containing at least 4 active
hydrogens or combinations of initiators where the mole average of active
hydrogens is at least 4, preferably from about 4 to about 8, and more
preferably from about 6 to about 8. Active hydrogens are defined as those
hydrogens which are observed in the well-known Zerewitinoff test, see
Kohler, Journal of the American Chemical Society, p. 3181, Vol. 49 (1927).
Representative of such active hydrogen-containing groups include --OH,
--COOH, --SH and --NHR where R is H or alkyl, aryl aromatic group and the
like.
Examples of suitable initiators include pentaerythritol, carbohydrate
compounds such as lactose, .alpha.-methylglucoside,
.alpha.-hydroxyethylglucoside, hexitol, heptitol, sorbitol, dextrose,
manitol, sucrose and the like. Examples of suitable aromatic initiators
containing at least four active hydrogens include aromatic amines such as
toluene diamine and methane diphenylamine, the reaction product of a
phenol with formaldehyde, and the reaction product of a phenol with
formaldehyde and a dialkanolamine such as described by U.S. Pat. Nos.
3,297,597; 4,137,265 and 4,383,102 (incorporated herein by reference).
Other suitable initiators which may be used in combination with the
initiators containing at least four active hydrogens include water,
glycerine, trimethylolpropane, hexane triol, aminoethylpiperazine and the
like. These initiators may contain less than four active hydrogens and
therefore can only be employed in quantities such that the total mole
average of active hydrogens per molecule remains at least about 3.5 or
more. Particularly preferred initiators for the preparation of the high
functionality, high molecular weight polyols comprise sucrose, dextrose,
sorbitol, .alpha.-methylglucoside, .alpha.-hydroxyethylglucoside which may
be employed separately or in combination with other initiators such as
glycerine or water.
The polyols may be prepared by methods well-known in the art such as taught
by Wurtz, The Encyclopaedia of Chemical Technology, Vol. 7, p. 257-266,
Interscience Publishers Inc. (1951) and U.S. Pat. No. 1,922,459. For
example polyols can be prepared by reacting, in the presence of an
oxyalkylation catalyst, the initiator with an alkylene oxide. A wide
variety of oxyalkylation catalysts may be employed, if desired, to promote
the reaction between the initiator and the alkylene oxide. Suitable
catalysts include those described in U.S. Pat. Nos. 3,393,243 and
4,595,743, incorporated herein by reference. However, it is preferred to
use as a catalyst a basic compound such as an alkali metal hydroxide,
e.g., sodium or potassium hydroxide, or a tertiary amine such as
trimethylamine.
The reaction is usually carried out at a temperature of about 60.degree. C.
to about 160.degree. C., and is allowed to proceed using such a proportion
of alkylene oxide to initiator so as to obtain a polyol having a hydroxyl
number ranging from about 200 to about 650, preferably about 300 to about
550, most preferably from about 350 to about 500. The hydroxyl number
range of from about 200 to about 650 corresponds to an equivalent weight
range of about 86 to about 280.
Polyols of higher hydroxyl number than 650 may be used as optional
ingredients in the process of the present invention. Amine-based polyols
having OH values greater than 650, preferably greater than 700 are
particularly useful as optional ingredients.
The alkylene oxides which may be used in the preparation of the polyol
include any compound having a cyclic ether group, preferably an
.alpha.,.beta.-oxirane, and are unsubstituted or alternatively substituted
with inert groups which do not chemically react under the conditions
encountered whilst preparing a polyol. Examples of suitable alkylene
oxides include ethylene oxide, propylene oxide, 1,2- or 2,3-butylene
oxide, the various isomers of hexane oxide, styrene oxide,
epichlorohydrin, epoxychlorohexane, epoxychloropentane and the like. Most
preferred, on the basis of performance, availability and cost are ethylene
oxide, propylene oxide, butylene oxide and mixtures thereof, with ethylene
oxide, propylene oxide, or mixtures thereof being most preferred. When
polyols are prepared with combinations of alkylene oxides, the alkylene
oxides may be reacted as a complete mixture providing a random
distribution of oxyalkylene units within the oxide chain of the polyol or
alternatively they may be reacted in a step-wise manner so as to provide a
block distribution within the oxyalkylene chain of the polyol.
Such polyols include a sucrose-initiated polyol propoxylated to an average
hydroxyl number of from about 400 to about 500, a sorbitol-initiated
polyol propoxylated to an average hydroxyl number of about 250 to about
290, a sorbitol-glycerine initiated polyol having nominally an average of
about 4.0 to about 4.4 active hydrogens and propoxylated to a hydroxyl
number of about 250 to about 290.
The polyol is used in a quantity sufficient to allow the preparation of low
friability, good dimensionally stable and strong foams having a thermal
conductivity of less than about 0.120 Btu-in./hr.ft.sup.2 .degree.F.
Suitable optional polyols include polyether polyols, polyester polyols,
polyhydroxy-terminated acetal resins, hydroxy-terminated amines and
polyamines. Examples of these and other suitable materials are described
more fully in U.S. Pat. No. 4,394,491, particularly in columns 3 to 5
thereof. Most preferred for preparing rigid foams are those having from
about 2 to about 8, preferably from about 3 to about 8 active hydrogens
and having a hydroxyl number from about 50 to about 800, preferably from
about 200 to about 650, and more preferably from about 300 to about 550.
Examples of such polyols include those commercially available under the
product names Terate (available from Cape Industries) and Multranol
(available from Mobay Corporation).
Other components useful in producing the polyurethanes of the present
invention include surfactants, pigments, colorants, fillers, antioxidants,
flame retardants, stabilizers, etc.
When preparing polyisocyanate-based foams, it is generally advantageous to
employ a minor amount of a surfactant to stabilize the foaming reaction
mixture until it obtains rigidity. Such surfactants advantageously
comprise a liquid or solid organosilicon compound. Other, less preferred
surfactants include polyethylene glycol ethers of long chain alcohols,
tertiary amine or alkanolamine salts of long chain alkyl acid sulfate
esters, alkylsulfonic esters, alkylarylsulfonic acids. Such surfactants
are employed in amounts sufficient to stabilize the foaming reaction
mixture against collapse and the formation of large, and uneven cells.
Typically, about 0.2 to about 5.0 parts of the surfactant per 100 parts
per weight polyol composition are sufficient for this purpose.
One or more catalysts for the reaction of the polyol and water with the
polyisocyanate are advantageously used. Any suitable urethane catalyst may
be used including the known tertiary amine compounds and organometallic
compounds.
Examples of suitable tertiary amine catalysts include triethylenediamine,
N-methylmorpholine, pentamethyldiethylenetriamine,
dimethylcyclohexylamine, tetramethylethylenediamine,
1-methyl-4-dimethylaminoethyl-piperazine, 3-methoxy-N-dimethylpropylamine,
N-ethylmorpholine, diethylethanolamine, N-cocomorpholine,
N,N-dimethyl-N',N'-dimethylisopropyl-propylenediamine,
N,N-diethyl-3-diethylaminopropylamine and dimethylbenzylamine. Examples of
suitable organometallic catalysts include organomercury, organolead,
organoferric and organotin catalysts, with organotin catalysts being
preferred. Suitable organotin catalysts include tin salts of carboxylic
acids such as dibutyltin di-2-ethyl hexanoate and dibutyltin dilaurate.
Metal salts such as stannous chloride can also function as catalysts for
the urethane reaction. A catalyst for the trimerization of
polyisocyanates, such as an alkali metal alkoxide or carboxylate, may also
optionally be employed herein. Such catalysts are used in an amount which
measurably increases the rate of reaction of the polyisocyanate. Typical
amounts are about 0.01 to about 1 part of catalyst per 100 parts by weight
of polyol.
The components described may be employed to produce rigid polyurethane and
polyurethane-modified isocyanurate foam. The isocyanate-reactive compound
having an OH value of from about 200 to about 650 and any other optional
polyol are reacted with an organic polyisocyanate in the presence of
blowing agent, catalyst, surfactant, additives, fillers, etc. The rigid
foams of the present invention may be made in a one-step process by
reacting all of the ingredients together at once, or foams can be made by
the so-called "quasi-prepolymer method." In the one-shot process where
foaming is carried out in machines, the active hydrogen-containing
compounds, catalyst, surfactants, blowing agents and optional additives
may be introduced separately to the mixing head where they are combined
with the polyisocyanate to give the polyurethane-forming mixture. The
mixture may be poured or injected into a suitable container or molded as
required. For use of machines with a limited number of component lines
into the mixing head, a premix of all the components except the
polyisocyanate can be advantageously employed. This simplifies the
metering and mixing of the reacting components at the time the
polyurethane-forming mixture is prepared.
Alternatively, the foams may be prepared by the so-called
"quasi-prepolymer" method. In this method a portion of the polyol
component is reacted in the absence of catalysts with the polyisocyanate
component in proportion so as to provide from about 10 percent to about 30
percent of free isocyanate groups in the reaction product based on the
prepolymer. To prepare foam, the remaining portion of the polyol is added
and the components are allowed to react together in the presence of
catalysts and other appropriate additives such as blowing agent,
surfactant, etc. Other additives may be added to either the prepolymer or
remaining polyol or both prior to the mixing of the components, whereby at
the end of the reaction a rigid polyurethane foam is provided.
The polyurethane foams of this invention have a thermal conductivity of
less than about 0.130, preferably less than about 0.120
Btu-in./hr.ft.sup.2 .degree.F., are useful in a wide range of
applications. Accordingly, not only can rigid appliance foam be prepared
but spray insulation rigid insulating board stock, laminates and many
other types of rigid foam can easily be prepared with the process of this
invention.
Having thus described my invention, the following Examples are given as
being illustrative thereof. All parts and percentages given in these
Examples are parts by weight and percentages by weight, unless otherwise
indicated.
EXAMPLES
The materials used in the Examples given below were as follows:
POLYOL A: a sucrose-based polyether polyol which is commercially available
under the name Multranol 4034 from Mobay Corporation having more than 4
isocyanate reactive hydrogen atoms and a hydroxyl number of 470.
POLYOL B: a high functionality polar aromatic polyester polyol derived from
a dimethyl terephthalate coproduct which is commercially available under
the name Terate 552 from Cape Industries having a hydroxyl number of
approximately 420.
POLYOL C: an amine based polyol which is commercially available from Mobay
Corporation having a functionality of four and an OH value of 770.
SURFACTANT A: a polyalkyleneoxide dimethyl siloxane copolymer, commercially
available from Union Carbide under the designation L-5440.
CATALYST A: a strongly basic, amber-brown liquid having a characteristic
amine odor which is commercially available from Air Products and
Chemicals, Inc. under the name Polycat 41.
CATALYST B: N,N,N',N'-tetramethyl hexamethylene diamine
CATALYST C: a tertiary amine catalyst which is commercially available from
Air Products and Chemicals, Inc. under the name Polycat 8.
Catalyst D: dibutyltin dilaurate.
HCFC-123: 1,1-dichloro-2,2,2-trifluoroethane.
HCFC-141b: dichlorofluoroethane.
POLYISOCYANATE A: a modified polymethylene polyphenyl polyisocyanate
prepolymer which is commercially available under the name Mondur E-577
from Mobay Corporation having an isocyanate group content of approximately
29.5%.
POLYISOCYANATE B: Mondur MR isocyanate, a commercially available
polymethylene polyphenyl polyisocyanate from Mobay Corporation, having an
NCO content of about 31%.
With the exception of the polyisocyanate, all of the ingredients included
in the formulations specified in Table 1 were combined in the amounts
indicated. The isocyanate was then added to the mixture in the amount
indicated in Table 1. The mixture which was maintained at a temperature of
about 20.degree. C. was then stirred with an air stirrer for approximately
5 seconds and poured into a cardboard box lined with plastic. The
properties of the resultant foams are given in Table 1.
TABLE 1
__________________________________________________________________________
Example 1 2 3 4 5 6 7 8 9 10 11
__________________________________________________________________________
Polyol A (pbw)
27.95
29.76
30.20
31.20
32.42
33.40
67.00
69.70
70.48
72.26
73.50
Polyol B (pbw)
22.36
23.80
24.16
24.96
25.94
26.72
-- -- -- -- --
Polyol C (pbw)
5.59
5.95
6.04
6.24
6.49
6.68 -- -- -- -- --
Stabilizer (pbw)
1.70
1.80
1.90
1.95
2.10
2.20 1.50
1.60
1.70
1.80
1.90
Catalyst A (pbw)
0.85
0.80
0.75
0.70
0.65
0.60 -- -- -- -- --
Catalyst B (pbw)
1.55
1.45
1.35
1.25
1.15
1.05 -- -- -- -- --
Water (pbw) -- 0.34
0.60
1.20
1.80
2.40 -- 0.32
0.64
1.00
1.30
HCFC-123 (pbw)
40.00
36.10
35.00
32.50
29.45
26.90
-- -- -- -- --
HCFC-141b (pbw)
-- -- -- -- -- -- 29.12
26.00
24.80
22.56
20.92
Polyisocyanate A (pbw)
84.1
96.2
102.7
117.6
133.2
147.9
-- -- -- -- --
Polyisocyanate B (pbw)
-- -- -- -- -- -- 77.3
85.3
91.1
98.7
104.7
Catalyst C (pbw)
-- -- -- -- -- -- 2.10
2.10
2.10
2.10
2.10
Catalyst D (pbw)
-- -- -- -- -- -- 0.28
0.28
0.28
0.28
0.28
Cream Time (sec)
13 12 13 13 13 13 20 22 23 24 22
Gel Time (sec)
34 31 34 33 34 35 42 44 48 48 46
Tack Free (sec)
50 52 52 51 53 55 48 55 60 60 56
Friability (5 min)
none
none
none
none
slight
moderate
-- -- -- -- --
Density (lbs/ft.sup.3)
1.52
1.59
1.58
1.52
1.55
1.53 1.63
1.70
1.65
1.68
1.63
K-factor 0.118
0.117
0.118
0.122
0.125
0.128
0.125
0.128
0.131
0.139
0.139
##STR1##
__________________________________________________________________________
Example 12 13 14 15 16 17 18 19 20 21
__________________________________________________________________________
Polyol A (pbw)
31.60
32.93
33.33
34.08
35.05
59.70
63.11
64.22
66.53
68.24
Polyol B (pbw)
25.28
26.34
26.66
27.28
28.04
-- -- -- -- --
Polyol C (pbw)
6.32
6.58
6.67
6.82
7.01 -- -- -- -- --
Stabilizer (pbw)
1.80
1.85
1.90
2.00
2.10 1.60
1.70 1.80 1.90 2.00
Catalyst A (pbw)
0.90
0.85
0.80
0.75
0.70 -- -- -- -- --
Catalyst B (pbw)
1.70
1.60
1.50
1.40
1.30 -- -- -- -- --
Water (pbw) -- 0.35
0.64
1.28
1.90 -- 0.30 0.60 0.90 1.20
HCFC-123 (pbw)
-- -- -- -- -- 36.70
33.00
31.50
28.69
26.47
HCFC-141b (pbw)
32.40
29.50
28.50
26.70
23.90
-- -- -- -- --
Polyisocyanate A (pbw)
95.0
105.9
112.9
127.8
143.0
-- -- -- -- --
Polyisocyanate B (pbw)
-- -- -- -- -- 68.9
77.4 83.6 90.6 97.1
Catalyst C (pbw)
-- -- -- -- -- 1.80
1.70 1.70 1.80 1.90
Catalyst D (pbw)
-- -- -- -- -- 0.20
0.19 0.18 0.18 1.19
Cream Time (sec)
11 11 11 12 11 28 30 35 30 25
Gel Time (sec)
28 28 28 29 28 47 49 55 57 50
Tack Free (sec)
44 44 45 46 45 58 62 75 76 64
Friability (5 min)
none
none
none
slight
moderate
none
none none none none
Density (lbs/ft.sup.3)
1.55
1.54
1.55
1.52
1.49 1.76
1.73 1.65 1.63 1.69
K-factor 0.117
0.118
0.120
0.124
0.126
0.132
0.126
0.129
0.131
0.129
##STR2##
__________________________________________________________________________
Although the invention has been described in detail in the foregoing for
the purpose of illustration, it is to be understood that such detail is
solely for that purpose and that variations can be made therein by those
skilled in the art without departing from the spirit and scope of the
invention except as it may be limited by the claims.
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